hollick



2 Sheets-Shut I.

No. 6l9,307 Patented Feb. l4, I899. T. D. 8. F. W. HULLICK.

ELECTRIC MOTOR.

(Apphcntlon filed Dec 22 1897 (No Model.)

Patented Feb. 14, I899.

T. D. &. F. W. HOLLICK. ELECTRIC MOTOR.

(Application filed Dec. 22, 1897.)

2' Sheets-Sheet 2.

(No Model.)

UNITED STATES PATENT OFFICE.

THOMAS DRAKE HOLLIOK AND FREDERICK WILLIAM HOLLIOK, OF LONDON, ENGLAND, ASSIGNORS OF ONE-THIRD TO JOHN CHARLES HOWELL, OF

SAME PLACE.

ELECTRIC MOTOR.

SPECIFICATION forming part of Letters Patent No. 619,307, dated February 14, 1899.

Application filed December 22,1897. Serial No. 663,051. (No model.)

To all whom it may concern:

Be it known that we, THOMAS DRAKE HOL- LICK and FREDERICK WILLIAM HoLLIoK, subjects of the Queen of Great Britain, re-

siding at London, England, have invented certain new and useful Improvements in Electromotors, (for which we have obtained a patent in Great Britain, numbered 14,493 and bearing date the 30th day of July, 1895,) of

[O which the following is a specification.

Our invention relates to improvements in electromotors in which motive power is obtained by means of electricity; and the objects of our invention are to provide means [5 by which while the electromotive force remains practically constant the speed shall be capable of being varied, so that it may be altered and regulated as required by the va' riations of load or the work to be done; also,

to provide means by'which the times when such alterations are required may be automatically indicated.

In order that our invention may be clearly understood, reference is made to the accom- 2 5 panying drawings, in which- Figure 1 is a side view, Fig. 2 is a front view, and Fig. 3 a back View, of an electromotor constructed according to our invention. Figs. 4, 5, 6, and 7 show in diagrammatic form different positions of the field-magnet.

Similarletters referto similar parts through out the several views.

Assuming that our invention is to be applied to an electromotor used, forexample,

5 for the purpose of propelling a tram-car, we

use a motor provided with an ordinary armature d, having a soft-iron core of suflicient length mounted upon a spindle Z, turning in bearings in the frames z of the motor and 0 having a commutator e and brushes of the usual kind, to which the conducting-wires F F, by which the current is supplied, are connected. The armature d is surrounded by a field-magnet A,- of which a or represent the poles, and Z) I) the exciting-coils, which are shunt-wound in the ordinary well-known rigidly in or upon guides c 0, attached to the frame or bed-plate B of the motor, so that it can be moved longitudinally in a direction parallel with the spindle Z of the armature d for a suflicient distance, as hereinafter explained. Adjoining or close to the first armature d we mount and fix upon the same spindle a second armature f, having a softiron core suitably wound, as hereinafter described, and also provided with a commutator and brushes e, connected with the conducting-wires F F.

When the field-magnet A is in such a position in or upon its guides c c that its poles at a entirely surround or inclose the first armature d in the direction of their length, as shown in Figs. 1 and 4, the armatures and shaft or spindle Z will revolve at a certain definite speed, the current through the second armature f being switched off and the circuit open. If now the field-magnet A is moved upon its guides c c in the direction of the second armature f until only one-half of the length of the first armature d is surrounded by it, (the current through the conductingwires with which the armature f is wound remaining switched 01%,) the number of revolutions of the armatures and of the shaft will be doubled, and so on proportionally. This position of the field-magnet is shown in the diagram Fig. 5. The movement of the fieldmagnet A longitudinally, as described, will of course have brought it partly over the second armature f. We have found, however, that the result describedthat is to say, the increase of speed of the armature d as the field-magnetAis withdrawn from itcannot be continued with efficiency beyond certain limits. In the case, for example, of an armature d fifteen inches long and nine inches in diameter, which proportions we have found give good results, an increase ofspeed up to about four to one can be obtained.

As already explained, the electrical current through the conducting-wires around the second armature f is switched off and allowed to remain open, (in the position shown in Figs. 1, 4, and 5,) and we find that the iron core of this armature f has the effect of keeping the magnetic field in the proper condition.

Supposing now that the field-magnet A is moved still farther, as shown in Fig. 6, so that about three inches of the first armature (Z still remains surrounded by it, while about twelve inches of the length of the field-magnet surrounds the second armature f, the latter has been wound with such a number of turns and with such thickness of conductingwire that a length of about twelve inches of this armature f will give a speed of revolution equal to or somewhat greater than the highest speed of the first armature cl. At this speed attained with this position of the field-magnet A the current through the coils of the first armature (Z is switched off by a switch, which may be of any of the kinds ordinarily known and used by electricians, the circuit around the second armature f being at the same time closed and the current switched on. (See Fig. 6.) In this condition the speed of the armatures d andfand their spindle Z can be still further increased by moving the field-magnet A back or in the direction opposite to that already described until only a part of the second armature f remains surrounded by it, as shown in Fig. 7, its overhanging part surrounding a corresponding part of the first armature d, the current through the conducting-wires around the latter remaining switched off, in which condition its iron core serves to keep the magnetic field in the proper required condition in the same way as has already been described in reference to the second armature f. The current through the conducting wires is switched on and off by ordinary switches at the times required. These switches are omitted in the drawings for the sake of clearness; but Figs. at, 5, 6, and 7 show the varying condition of the circuit through the two armatures.

Supposing that a motor constructed and operating in the novel way described makes one hundred revolutions per minute when the whole of the first armature d is surrounded by the field-magnet A (see Figs. 1 and 4) and that when the field-magnet A has been shifted, as described, until it surrounds the whole of the second armature f, while still surrounding about three inches of the armature d, (see Fig. 6,) the speed of four hundred revolutions per minute is reached, and this speed is maintained by closing the circuit and switching on the current through the coils of the second armature f and opening the circuit and switching off the current through the coils of the first armature d, as indicated in Fig. 6. Then if the field-magnet A is shifted still farther back, so as to uncover one-half of the length of the second armature f, as shown in Fig. 7, a speed of about double the last mentioned,or, say, eight hundred revolutions, can be attained.

The conducting-wires to the armatures cl and f are indicated at F and F, respectively, in Figs. 4, 5, 6, and 7; but it is of course to be understood that these wires are connected to brushes and commutators of the usual kind, through which the current is supplied to the coils around the armatures. In some cases the conducting-wire around the second armature f and the commutator and brushes may be omitted altogether, in which case the partf simply forms an iron core for the purpose of maintaining the magnetic field in a proper condition.

We are aware that it has been proposed to efiect the object desired by the use of a single armature and field-magnet and variable resistances, or by varying the relative position of the field-magnets to the armature by moving the poles of the former transversely nearer to or farther from the armature, or bymoving longitudinally an armature, so as to be more or less surrounded by a field-magnet; but such methods have proved ineffective or objectionable in action.

By our invention we are able to attain the desired results simply and efficiently, while the variation of speed is effected within very wide limits, but perfectly gradually and not in a succession of steps, as is the case where resistances are used, a motor constructed and operating in the novel manner described being easily worked and very efficient, while resistances of the kinds ordinarily used when starting or varying the speed are entirely dispensed with.

The field-magnet A may be moved by an attendant longitudinally along the guides c c to the different positions required in relation to the armatures by different appliances. In the drawings it is shown operated by a screw y, turning in bearings in the frame of the motor, the screw passing through a nut in the base of the field-magnet A. At the front end of the screwy is fixed a beveled toothed wheel (1;, gearing with a similar one 00' upon a vertical spindle to, turning in bearings carried by the frame of the motor and having at its upper end a conical friction-wheel o, driven by one or other of the corresponding conical frictional wheels to and it upon a coupling t, sliding (without turning) upon the spindle Z of the motor. The coupling t is moved in one or other direction by the levers, operated by the attendant. In the position shown the wheel a drives the wheel 1), and the screw 1 is consequently turned so that the field-magnet A is moved to the left hand and is shown in Figs. 1 and i at the end of its course to the left. When (on account of a reduction in the load or when the tram-car is going downhill) the current of electricity is reduced, the lever s is moved until the wheel it (instead of it) drives the wheel "0, and the screwy is consequently turned so that the field-magnet A is moved to the right hand, and so on, according to the constant varying requirements which the attendant meets by means of the lever .9. When the current is correctly proportioned to the work required, the leversis brought to its central position, and the fieldmagnet A remains stationary.

In Figs. 1 and 2 the lever s is shown influenced by a solenoid 0, through which the current of one or other of the armatures d f is made to pass, connections for same being not shown. The core 13, fitting in the solenoid 0, is connected with the lever s, and the current passing around it tends to draw the lever into the position shown in Fig. 1. An adjustable spring 7 is also connected with the lever s and acts upon the latter in the opposite direction to the solenoid 0. If, therefore, the current through the solenoid is just suflicient to balance the pull of the spring 7', the lever 3 remains in its central position and the fieldmagnet A remains stationary. hen, however, through an increase of load or work to be done by the motor, the current through the solenoid 0 increases, its attract-ion overcomes the resistance of the spring r, and the lever s is brought to the position shown, causing the field-magnet A to be moved to the left until it reaches the position shown in Fig. 1. The attendant then (or sooner, if necessary) brings back the lever s to its central position and retains it there until an alteration of the position of the field-magnet is again required, according to the system first described. If, on the other hand, through a decrease of the load or work required from the motor the current through the solenoid decreases, the spring 0" overcomes its attraction and brings over the lever 8 into a position where the wheel u comes into contact with v, and the screw y is turned so that the field-magnet is moved to the right until the attracting force of the solenoid again increases or the lever is brought to its central position by the attendant. Itis evident, however, that instead of utilizing the power of the motor to vary the position of the fieldinagnet A, as described, this can be done by the attendant himself turning the screw y by means of a handle or equivalent gear, or in stead of the screw 3 and nut equivalent mechanical devices, such as a rack and pinion or an endless cord or chain attached to the field-magnet Aand passing around pulleys carried by the frame of the motor, may be used. Either the pinion gearing with the rack or one of the pulleys around which the cord or chain passes is turned in the required direc tion by the attendant.

We do not claim the broad combination of a single armature with a movable and adj ustable field-magnet; but

WVhat we claim as our invention, and desire to secure by Letters Patent, is

1. In electromotors and in combination, an armature-shaft, two separate armatures, the main armature having a greater length than diameter, mounted thereon, and a field-magnet movable with relation to the armatures to surround one or a portion of both armatures, substantially as set forth.

2. In electromotors and in combination, an armature shaft, two separate armatures, mounted thereon, a fieldmagnet movable with relation to the armatures to surround one or a portion of both armatures, an electromagnet through which the current from the wound armature or armatures passes and means for causing the field-magnets to be moved in one or other direction depending upon the current passing through the electro-' magnet substantially as set forth.

3. In combination with the movable fieldmagnet A the two adjoining armatures d and fupon the motor-shaft Z, armature f being wound with regard to winding on armature d in such manner that the speed of armature f when within field a is approximately equal to highest speed attained by armature d, substantially as and for the purposes set forth.

4:. The combination with means for moving the field-magnet longitudinally, of a fixed solenoid adapted to receive current from one or the other of the armatures, movable core 1), adjustable spring 7', lever s, clutch 25, conical friction-wheels an, on the motor-shaft Z, conical friction-wheel o, spindle w, and conical toothed wheels-m 00, all arranged and operating substantially as set forth.

In testimony whereof we have hereunto set our hands in the presence of two subscribing witnesses.

THOMAS DRAKE IlOLLlOK. FREDERICK WILLIAM HOLLIOK. Witnesses:

FRED O. HARRIS, T. J. OSMAN. 

